1. Field of the Invention
The invention relates to an umbrella frame, hereinafter referred to as of the kind described, comprising a stick carrying a crown and a slider, canopy spokes pivotally connected to the crown and struts pivotally connected to the slider; wherein at least one of the pivotal connections comprises a substantially cylindrical sheet metal sleeve which is carried by the stick, and which is provided at one end with a star-like array of radially outwardly projecting lobes, separated from one another by radial slits in which the inner ends of respective ones of the spokes or struts are hinged by means of at least one pivot pin which is located within inwardly curled portions of the lobes.
2. Description of Related Art
Umbrella frames of this kind, the hinges of which allow assembly by machine, are already known, for example, from the U.S. Pat. No. 958,341 to Wetteroth isued May 17, 1910, and U.S. Pat. No. 1,290,245 to Kuehner issued Jan. 7, 1919. For pivotally connecting the canopy spokes, in accordance with the U.S. Pat. No. 958,341 to Wetteroth an umbrella crown, which can be displaced along the stick of the umbrella by means of a cylindrical sleeve, is provided. Lobes are fashioned directly onto the sleeve to run radially outwards, in the form of a star transverse to the open end of the sleeve, and the number of lobes corresponds with the number of canopy spokes which have to be pivotally connected to the sleeve. The lobes are separated from one another by slits, in each of which a canopy spoke is hinged by means of an axle ring concentric with the sleeve and arranged at a radial clearance from the sleeve. This axle ring is attached to the sleeve by the lobes being curled round the axle ring so that they point inwards towards the axis of the sleeve.
For pivotally connecting the canopy spokes onto the crown of the umbrella frame, the ends are in the form of hooks which are hooked through the slits and round the axle ring. In order to avoid damage to an umbrella cover by any exposed sharp edges on the crown, the axle ring, with the ends of the canopy spokes hooked in, is encased from above by a protective cap. This protective cap is supported on a shoulder formed between the sleeve and the hinge lobes.
It is a disadvantage, in the case of this umbrella frame, that the assembly by machine of the umbrella hinges, canopy spokes and struts demands relatively complicated techniques. In order to be able to curl in the lobes round the axle ring, both the sleeve and the axle ring must be fixed in position concentrically be means of a tool. In particular, it is necessary to adjust the axle ring to be exactly concentric with the sleeve, since otherwise the whole umbrella frame geometry of the canopy spoke is incorrect upon hinging it onto the axle ring. Furthermore, it is a disadvantage that the lobes are fashioned directly onto the sleeve and that the dividing slits between the lobes are cut in right up to the sleeve. Forces arise, upon curling the lobes round the axle ring, which may easily lead to deformation of the sleeve so that it can no longer be mounted on the stick of the umbrella. Furthermore, the star formation of the lobes when curled round the axle ring is very easily damaged by bending. Even slight jerks, say, upon folding the umbrella or in the case of careless handling or dropping, may very easily deform it.
In the case of an umbrella frame in accordance with U.S. Pat. No. 1,290,245 to Keuhner, the lobes merge directly onto the surface of the sleeve. In this case as well, undesirable deformations of the sleeve upon curling in the lobes, or in the case of improper handling of the umbrella, cannot be avoided. Furthermore, the canopy spokes and struts, because of the proximity of their hinges to the sleeve, have insufficient play in their hinges to be able to rotate freely.